Many disabled children, such as those suffering from cerebral palsy and muscular dystrophy for example, need additional support when occupying a wheelchair, as otherwise they cannot remain erect or properly seated and may even go into spasm with the result that they fall or at least collapse into an uncomfortable and sometimes dangerous position if not securely strapped into the chair. Improperly seated children tend to develop pressure sores and there is a risk of increased spinal deformaties and respiration difficulties which make it risky to leave a disabled child unattended in a conventional wheelchair or the like.
There are a number of chairs presently available which are designed so that the shape of the seat and back portions of the chair can be altered to make an able bodied person, and particularly an adult, more comfortable and less subjected to fatigue, but these are of little help when it comes to providing the type of seating which is required by disabled adults and children. When attempts are made to incorporate some of the structural features of known chairs into a specialized seat for a disabled person, it is generally found that such a seat is expensive and requires a considerable amount of the time of a skilled technician attempting to fabricate and adjust the seat to meet the needs of particular individuals. The result has been that some treatment and rehabilitation centres have resorted to making seat inserts for conventional chairs. Such inserts are often cast of plaster or are otherwise formed to fit a particular child and are discarded and replaced periodically as the intended user grows or his condition changes.